CVE-2012-3864 in Puppet
Summary
by MITRE
Puppet before 2.6.17 and 2.7.x before 2.7.18, and Puppet Enterprise before 2.5.2, allows remote authenticated users to read arbitrary files on the puppet master server by leveraging an arbitrary user s certificate and private key in a GET request.
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Analysis
by VulDB Data Team • 12/07/2021
The vulnerability identified as CVE-2012-3864 represents a critical security flaw in the Puppet configuration management system that affects multiple versions of both the open source Puppet software and Puppet Enterprise. This vulnerability stems from inadequate access controls within the Puppet master server's certificate handling mechanism, allowing authenticated attackers to exploit the system's trust model by leveraging valid user certificates and private keys to gain unauthorized access to arbitrary files on the master server. The flaw specifically targets the way Puppet processes GET requests that contain certificate information, creating a path for privilege escalation and information disclosure.
The technical implementation of this vulnerability involves the exploitation of the certificate-based authentication system that Puppet uses to establish trust between clients and the master server. When an authenticated user submits a GET request containing their certificate and private key, the Puppet master server fails to properly validate the request parameters, allowing an attacker to manipulate the request to access files outside of the intended scope. This flaw operates at the application layer and leverages the trust relationship established through certificate authentication, making it particularly dangerous as it can be exploited by users who have legitimate access to the system but should not have broader file system access. The vulnerability aligns with CWE-284, which describes improper access control, and specifically relates to the weakness where insufficient checks are performed on the scope of operations permitted by authenticated users.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with the ability to access sensitive configuration files, private keys, and other critical system data that could be used for further attacks within the network. An attacker who successfully exploits this vulnerability can potentially gain access to other users' private keys, system configuration files, and potentially escalate their privileges to access additional systems within the Puppet-managed environment. The implications are particularly severe in enterprise environments where Puppet is used to manage critical infrastructure, as the compromise of a single authenticated user account could lead to widespread access to sensitive organizational data. This vulnerability also aligns with ATT&CK technique T1078 which covers valid accounts and T1566 which covers credential harvesting, as it exploits legitimate authentication mechanisms to gain unauthorized access.
Organizations affected by this vulnerability should immediately implement the patches released by Puppet Labs for versions 2.6.17 and 2.7.18, as well as Puppet Enterprise 2.5.2 and later. The recommended mitigation strategy involves not only applying the software updates but also implementing additional monitoring of GET requests to the Puppet master server for unusual patterns that might indicate exploitation attempts. Security teams should also review and tighten access controls for Puppet master server components, ensuring that users have the minimum necessary permissions and that certificate management processes are properly enforced. Additionally, network segmentation and firewall rules should be implemented to limit direct access to Puppet master servers from untrusted networks, reducing the attack surface and providing additional defense in depth measures against similar vulnerabilities. The vulnerability demonstrates the critical importance of proper input validation and access control enforcement in certificate-based authentication systems, as well as the need for comprehensive security testing of authentication mechanisms before deployment in production environments.